Conventionally, blowout of an offensive odor upon actuation of an air conditioner for vehicles has been problematic. As the reason for this offensive odor, mention can be made of the activity of microorganisms such as bacteria proliferated inside air conditioners. The inside of an air conditioner is an environment which favors bacterial proliferation because of dew condensation water adhering to an evaporator during operation of the air conditioner. By the action of a large amount of proliferated bacteria, the inside of an air conditioner is filled with an offensive odor. Antibacterial treatment and drying treatment in the inside of an air conditioner have been considered as countermeasures against this offensive odor.
There is a method of compounding an antibacterial agent into a resin inside an air conditioner as one of antibacterial treatments. In this method, however, the effect of an antibacterial agent is lost when dust accumulates on the antibacterial agent. As a countermeasure, use of a volatile antibacterial agent has been proposed (see, for example, Patent Documents 1 to 3). In the prior art inventions, a volatile antibacterial agent is placed inside the air conditioner. It is however difficult to apply the prior art inventions to an air conditioner for a motor vehicle. The temperature in a motor vehicle becomes very high in summer, and the temperature in an air conditioner can sometimes reach about 50° C. When the temperature is raised as just described, the amount of the antibacterial agent volatilized is increased, and thus the antibacterial agent is consumed in a short period of time.
To solve this problem, an invention directed to a case housing an antibacterial agent has been made (see, for example, Patent Document 4). In the Patent Document 4, attention is focused on that when a case using allyl isothiocyanate (AIT) as an antibacterial agent is made of polypropylene, a part of volatilized AIT passes through the polypropylene. By utilizing this characteristic, the volatilization rate of the volatile substance permeating through the case is controlled by housing the volatile substance in a gas-permeable bag and changing the thickness of the case and the surface area of the case.
Patent Document 1
Japanese Patent Laid-Open No. Hei 11-211126
Patent Document 2
Japanese Patent Laid-Open No. 2000-88270
Patent Document 3
Japanese Patent Koukoku No. Hei 6-78821
Patent Document 4
Japanese Patent Laid-Open No. 2004-224382